[Effect of Bufei Decoction on improving COPD mouse model by regulating MMP12/IL-17A immune response]

This study aims to investigate the effect of Bufei Decoction on the immune response and apoptosis of Th17 cells in chronic obstructive pulmonary disease(COPD) mice characterized by emphysema. Fifty C57BL/6 mice were randomly divided into a blank group, a model group, a Bufei Decoction group, an interleukin-17A(IL-17A) group, and a methylprednisolone group. A COPD mouse model characterized by emphysema was constructed by smoking and intraperitoneal injection of elastase and intervened by Bufei Decoction and IL-17A monoclonal antibody. An animal lung function analyzer was used to detect mouse lung function. Hematoxylin and eosin(HE) staining was utilized to observe pathological changes. Western blot was employed to detect the expression of B-cell lymphoma/leukemia-2 protein(Bcl-2), Bcl-2-associated X protein(Bax), cysteine aspartic acid protease-3(caspase-3), and cleaved cysteine aspartic acid protease-3(cleaved caspase-3) in lung tissue, and enzyme-linked immunosorbent assay(ELISA) was used to measure the content of matrix metalloproteinase 12(MMP12) and IL-17A and the expression of inflammatory factors interleukin-6(IL-6) and interleukin-8(IL-8) in bronchoalveolar lavage fluid. Flow cytometry was used to detect the apoptosis rate and T lymphocytes CD4~+ and CD8~+. The results showed that compared with that in the blank group, HE staining of lung tissue in the model group was consistent with the pathological changes of COPD. The ratio of the maximum expiratory volume 0.2 seconds after expiration to the forced expiratory volume(FEV0.2/FVC), the average flow rate of expiratory volume accounting for 25% to 75% of lung capacity(MMEF), and peak expiratory flow(PEF) in lung function testing were significantly reduced, and the content of MMP12, IL-17A, IL-6, IL-8, and CD8~+ was significantly increased. The apoptosis rate of lung tissue cells and the expression of pro-apoptotic proteins Bax and cleaved caspase-3 were significantly increased, and the expression of anti-apoptotic protein Bcl-2 was significantly reduced. Compared with the model group, the Bufei Decoction group showed a significant decrease in the expression of MMP12, IL-17A, Bax, and cleaved caspase-3, a significant reduction in the content of CD8~+ and the apoptosis rate, and a significant increase in the expression of anti-apoptotic protein Bcl-2. Bufei Decoction may regulate the immune and inflammatory responses mediated by MMP12 and IL-17A and reduce the apoptosis of lung tissue cells to alleviate COPD characterized by emphysema.